Enclosed media fluid filtration device

ABSTRACT

A filtration device comprising a media basket, a baseplate, and a canister. The media basket is affixed to the baseplate. The canister has a cavity therein and is detachably coupled with the baseplate to enclose the media basket. The media basket contains a porous filtration material that efficiently removes contaminants from liquid. The device is configured to establish a first siphon to convey liquid from outside the device into the canister cavity through a canister pipe when a liquid level outside the filtration device is higher than the top of the weir in the canister pipe and configured to establish a second siphon to convey liquid from canister cavity through the top of a center riser pipe and out an outlet pipe when the first siphon has been established and the liquid level outside the filtration device is higher than the top of the center riser pipe.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation application of applicationSer. No. 14/924,669, filed Oct. 27, 2015, incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates to filtration of contaminants from aliquid. More particularly, the present invention relates to thefiltration of contaminants in stormwater through a vertical passivesiphon operated filter.

BACKGROUND

Removal of contaminants by filtration is commonly used and acceptedpractice in stormwater applications as a method for capturing fineparticles. Filters employ a various array of media that captureparticulate matter by bonding or capture. The media is typicallygranular and is contained in a device or structure that allows mediacompaction. This increases the media density and increases the abilityof the media to remove fine particulate matter. Filters for stormwaterare usually passive devices and typically fall into two categories:Horizontal filters and vertical filters.

Horizontal filters can be used in an up-flow or down-flow configuration.In a down-flow application the flow rate is driven by gravity and in anup-flow configuration the flow rate is generated through hydraulic head.In both cases, an increase in the available water column increases theflow rate. Horizontal filters tend to be larger in size than verticalfilters as they achieve their surface area via a horizontal bed. Commontypes of horizontal filters include but are not limited to Sand Beds,Rain Gardens, and Swales. Horizontal filters can lose filtrationcapacity due to the plugging of the initial layer of media. Often timesthe media below the initial layer has sufficient capacity but theocclusion of the initial layer reduces the media lifespan. To regainfiltration capacity, it requires replacement or alteration of theinitial or entire media bed.

Vertical filters are often times modular, which facilitates deployingthem in series or parallel to achieve the desired flow rate. Verticalfilters are typically located inside a containment structure that oftentimes acts as a pre-settling device for larger particles. The verticalnature of these devices allows them to be compact and often times theyare located underground. Filtration media for vertical filters istypically contained within a screened device where the vertical screenacts as the surface area for the filtration. Flow rates through thefilter media are achieved via a difference in hydraulic head between theliquid in the containment vault and the filter outlet. The liquid can bedirectly conveyed by the pressure difference, or the hydraulic head isused to activate a siphon mechanism. Filters with siphon mechanismstypically achieve higher mean flow rates and obtain greater liquiddispersion within the media.

Vertical filters can still be subject to the plugging challenges ofhorizontal filters. Often times the floor of the containment structureaccumulates large amounts of settled sediment. The sediment depthaccrues and comes in direct contact with the filter media. When thefilter is under operation during a storm event the sediment can becomere-suspended in the liquid and increase the sediment loading on thefilter beyond its intended design. This causes premature media failureand more frequent maintenance. Another challenge for siphon operatedvertical filters is stagnant stormwater between operation cycles. Apassive siphon requires a fixed hydraulic water column within thecontainment structure to cause siphon actuation. Variations in stormfrequency and intensities can cause long periods in between operationcycles where the containment vault is partially full of stormwater butnot full enough to cause siphon activation. The partial submergence ofthe filter media for long periods can potentially cause adverse effectsand result in anaerobic conditions, organics growth, and potentiallycause premature occlusion.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described by way of exemplary embodiments,but not limitations, illustrated in the accompanying drawings in whichlike references denote similar elements, and in which:

The accompanying drawings, which are incorporated into and constitute apart of this specification, illustrate one or more embodiments of theinvention and, together with the detailed description, serve to explainthe principles and implementations of the invention.

FIG. 1 shows an exterior isometric view of an exemplary filtrationdevice.

FIG. 2 shows an overhead plan view of the exemplary filtration device.

FIG. 3 shows an assembled side profile view of the exemplary filtrationdevice taken along line 1-1 of FIG. 2 with arrows to depict liquiddirection during operation.

FIG. 4 shows an isometric section view of the interior of the exemplaryfiltration device without the canister.

FIG. 5 shows an overhead plan view taken along line 2-2 of FIG. 3.

FIG. 6 shows an isometric view of the cap of the exemplary filtrationdevice.

FIG. 7 shows a profile view taken along line 3-3 of FIG. 5.

FIG. 8 shows a profile view of the canister with cut section to depictinterior and exterior canister pipes.

FIG. 9 shows an overhead plan view of four exemplary filtration devicesin parallel installed in a containment structure.

FIG. 10 shows an isometric cross section view taken along line 4-4 ofFIG. 9.

FIG. 11 shows a top view of the device showing design variables as itrelates to the interior and exterior siphons.

FIG. 12 shows a cross-sectional view taken along Line 5-5 of FIG. 11showing design variables as it relates to the interior and exteriorsiphons.

DETAILED DESCRIPTION

Before beginning a detailed description of the subject invention,mention of the following is in order. When appropriate, like referencematerials and characters are used to designate identical, corresponding,or similar components in different figures. The figures associated withthis disclosure typically are not drawn with dimensional accuracy toscale, i.e., such drawings have been drafted with a focus on clarity ofviewing and understanding rather than dimensional accuracy.

In the interest of clarity, not all of the routine features of theimplementations described herein are shown and described. It will, ofcourse, be appreciated that in the development of any such actualimplementation, numerous implementation-specific decisions must be madein order to achieve the developer's specific goals, such as compliancewith application and business related constraints, and that thesespecific goals will vary from one implementation to another and from onedeveloper to another. Moreover, it will be appreciated that such adevelopment effort might be complex and time-consuming, but wouldnevertheless be a routine undertaking of engineering for those ofordinary skill in the art having the benefit of this disclosure.

Use of directional terms such as “upper,” “lower,” “above,” “below”, “infront of,” “behind,” etc. are intended to describe the positions and/ororientations of various components of the invention relative to oneanother as shown in the various Figures and are not intended to imposelimitations on any position and/or orientation of any embodiment of theinvention relative to any reference point external to the reference.

Those skilled in the art will recognize that numerous modifications andchanges may be made to the exemplary embodiment(s) without departingfrom the scope of the claimed invention. It will, of course, beunderstood that modifications of the invention, in its various aspects,will be apparent to those skilled in the art, some being apparent onlyafter study, others being matters of routine mechanical, chemical andelectronic design. No single feature, function or property of theexemplary embodiment(s) is essential. Other embodiments are possible,their specific designs depending upon the particular application. Assuch, the scope of the invention should not be limited by the particularembodiments herein described but should be defined only by the appendedclaims and equivalents thereof.

Exemplary Embodiment—Device Construction Description

FIGS. 1-3 show an exemplary embodiment of a filtration device 70. Theexemplary filtration device 70 comprises a media basket 40, a baseplate2, and a canister 22. The media basket 40 is affixed to the baseplate 2.The canister 22 has an open bottom as well as a top opening 66 locatedin a ceiling 68 of the canister 22. The canister 22 has a cavity 26therein and is detachably coupled with the baseplate 2 to enclose themedia basket 40. The media basket 40 contains a porous filtration media42 that efficiently removes contaminants from the liquid. In theexemplary embodiment, the media basket 40, the baseplate 2 and thecanister 22 are cylindrical in shape or at least have a circularcross-section, but in other embodiments may have a rectangular or othersuitable shape.

The baseplate 2 is a horizontal plate that is typically impermeable,flat, and round. The baseplate 2 is typically made of plastic andtypically molded, but in other embodiments may be made of other suitablematerials and made by other manufacturing methods. The baseplate 2contains two raised sections. The first raised section is the columnspigot 4. The column spigot 4 is a raised column configured for theattachment of a support column 24 as well as a connection point betweena center riser pipe 8 and an outlet pipe 7. In the exemplary embodiment,the column spigot 4 is cylindrical, but in other embodiments, may have arectangular or other shape. The support column 24 attaches to the columnspigot 4 via either a glued or mechanical connection. Additionally, onan interior bottom of the column spigot 4, one or more rigid buoyancytabs 12 are either molded into the baseplate or permanently affixed. Thepurpose of the buoyancy tabs 12 is to serve as points to affix theexemplary filtration device 70 to the floor of the containment structure1 to prevent flotation when there are unbalanced buoyant forces actingon the exemplary filtration device 70. The buoyancy tabs 12 interlockunderneath a buoyancy plate 14 that is permanently affixed to thecontainment structure 1 floor. In the exemplary embodiment, the buoyancyplate 14 is a cylindrical plate that is most likely made of plastic ormetal and is rigid to withstand the buoyant forces of the exemplaryfiltration device 70. In other embodiments the buoyancy plate 14 mayhave a square shape or shape other than cylindrical. The buoyancy plate14 has one or several thin locking protrusions 16 that allow thebuoyancy tabs 12 to slide underneath when the exemplary filtrationdevice 70 is horizontally rotated. When the exemplary filtration device70 experiences buoyant forces the buoyancy tabs 12 will transfer theforces into the locking protrusions 16 of the buoyancy plate 14 which ispermanently affixed to the floor of the containment structure 1 thuspreventing any movement.

The second raised section of the baseplate 2 is an outlet pipe cover 18.The outlet pipe cover 18 is a raised protrusion that runs radially fromthe column spigot 4 to the outer edge of the baseplate 2. The outletpipe cover 18 is configured to accommodate an outlet pipe 7 locatedbelow the baseplate 2 on the floor of the containment structure. Theoutlet pipe 7 is a horizontal pipe that is located directly below theoutlet pipe cover 18 and is most likely affixed to the floor of thecontainment structure 1. The outlet pipe 7 has a vertical bend 21 at ornear to the center of the column spigot 4. The vertical bend 21 of theoutlet pipe 7 is configured to facilitate a watertight slip connectionto the center riser pipe 8. This slip connection allows for removal ofthe exemplary filtration device 70 when maintenance is required.

The support column 24 is a vertical, rigid, permeable pipe that servesmultiple functions in the exemplary filtration device 70. A firstfunction of the support column 24 is to act as an attachment pointbetween the baseplate 2 and the canister 22. The bottom of the supportcolumn 24 is permanently affixed to the column spigot 4 while the top isconfigured for coupling with a cap 6 by threading or some other suitablemechanism. When the canister 22 is coupled with the support column 24,the threads of the support column 24 protrude through the canister topopening 66. The interior threads of the cap 6 are configured forscrewing onto the support column 24 threads. A cap gasket 52 ispositioned between the cap 6 and the canister 22. A portion of thecanister 22 near the canister top opening 66 rests on a column supportflange 28. The column support flange 28 is a perpendicular flange thatis permanently affixed or molded to the support column 24. The cap 6 istypically made of plastic or metal and has torque handles 60 that allowthe cap 6 to be torqued onto the support column 24 threads to compressthe canister 22 onto the baseplate 2. The canister 22 compresses abaseplate gasket 32 between the canister flange 34 and the baseplate 2.Both the baseplate gasket 32 and cap gasket 52 are typically made fromrubber, EPDM, or neoprene, but may be made of other suitable materials.When compression is sufficient between the canister flange 34 andbaseplate gasket 32, it creates a watertight connection.

The second function of the support column 24 is to act as an innerpartition for the filter media 42. The support column 24 has a pluralityof penetrations to allow the liquid to pass from the exterior of thesupport column 24 to the interior. The support column 24 has an innerpartition screen 38 is a plastic or metal mesh screen and that isaffixed around the circumference of the support column 24 such that itallows the liquid to pass through on all sides and for substantially allof its vertical height. The inner partition screen 38 is affixed to thesupport column 24 via a mechanical connection.

The center riser pipe 8 is a vertical pipe positioned inside the supportcolumn 24. The center riser pipe 8 has a bottom end that is permanentlyaffixed to the baseplate 2 at a center point of the column spigot 4 viaa glued or threaded watertight connection. The center riser pipe 8 has atop end that is unconnected and open. The top end of the center riserpipe 8 terminates above the level of the canister ceiling 68 and abovethe level of the top of the horizontal weir 9. On the bottom of thecenter riser pipe 8 there is a leach orifice 48. The leach orifice 48 isa small hole configured for allowing any remaining water inside theexemplary filtration device 70 to drain once the siphons have ceased.

Near the outer edge of the baseplate 2 there is an outer partitionflange 36. The outer partition flange 36 is a circumferential flangeconfigured for attachment of the media basket 40. The media basket 40 istypically attached to the outer partition flange 36 via a bolted orriveted mechanical connection. The filter media 42 can be one or more ofa multitude of different materials. The specific composition of thefilter media 42 can be tailored specifically to remove desiredcontaminants, based upon the installation location and/or expectedcontaminants. The filter media 42 may be tailored for capturingphysical, dissolved, and/or ionic contaminants. Potential example filtermaterials are perlite, carbon, sand, activated alumina, and peat.

The canister 22 is typically made from plastic or fiberglass reinforcedpolymer, but may be made of other suitable materials. The canister 22has one or more canister pipes 39, each comprising an exterior canisterpipe 41 and an interior canister pipe 45. During operation the exteriorcanister pipe 41 and interior canister pipe 45 act as a uniformconveyance pipe allowing siphon operation. The exterior canister pipes41 run vertically along the exterior of the canister 22. The exteriorcanister pipes 41 are configured to convey the contaminated liquid fromthe containment structure 1 into the exemplary filtration device 70. Theexterior canister pipes 41 are typically semi-circular or rectangular incross-section, but may be some other suitable shape. The exteriorcanister pipes 41 each have a sealed top and an exterior bottom orifice62 that is open to the environment. The exterior canister pipe 41 istypically made of plastic or some other suitable material. The exteriorcanister pipe 41 is either molded into the canister 22 or affixedpermanently to the side. The interior canister pipe 45 is typically amirror image to the exterior canister pipe 41, though in someembodiments there may be some variation in shape. The interior canisterpipe 45 is typically made of plastic or some other suitable material.The interior canister pipe 45 is permanently affixed to the interiorwall of the canister 22 and has a closed top and an interior bottomorifice 64. The canister 22 has a horizontal weir 9 separating theexterior canister pipe 41 from the interior canister pipe 45, except fora canister pipe chamber 44 above the top of the horizontal weir 9 thatallows the liquid to pass from the exterior canister pipe 41 to theinterior canister pipe 45.

A nappe deflector 49 may be affixed to the interior canister pipe 45side of the horizontal weir 9 near the top such that it will increasethe horizontal trajectory of the liquid as it passes from the exteriorcanister pipe 41 over the horizontal weir 9 to the interior canisterpipe 45. During operation the exterior canister pipe 41 and interiorcanister pipe 45 act as a uniform conveyance pipe allowing siphonoperation. In some embodiments, an exterior screen 47 may be affixed tothe outside of the canister 22 such that it encompasses the exteriorbottom orifice 62. This minimizes the potential for occlusion of theexterior canister pipe 41 orifice.

Exemplary Embodiment—Operation Description

Fluid is conveyed through the exemplary filtration device 70 via twounique siphons; an exterior siphon and an interior siphon. The exteriorsiphon conveys contaminated liquid into the exemplary filtration device70 while the interior siphon conveys treated liquid out of the exemplaryfiltration device 70. In the exemplary embodiment, the filtration device70 is affixed inside a containment structure 1 where liquid is conveyedinto the structure until it reaches an elevation in which the hydraulichead is sufficient enough to operate the interior and exterior siphonsthus conveying the liquid through the filter media 42 and into an outletmanifold 30 to downstream discharge.

The exemplary filtration device 70 can be used in a stand-alone ormodular configuration. In the exemplary embodiment, the exemplaryfiltration device 70 is affixed to the containment structure 1.Contaminated liquid is conveyed into the containment structure 1 viapipes, surface grates, downspouts, and/or open channels 29. Thecontainment structure 1 is typically an impermeable vault, manhole,and/or catch basin and is most likely made of concrete, steel, plastic,or potentially fiberglass. The containment structure 1 may allow anysuspended liquid contaminants to settle out prior to entering theexemplary filtration device 70. As liquid accumulates in the containmentstructure 1, the liquid elevation increases such that the liquid entersthe exemplary filtration device 70 via the exterior bottom orifices 62on the bottom of the exterior canister pipes 41. The exemplaryfiltration device 70 may employ multiple exterior canister pipes 41 toincrease the total incoming flow rate. As the liquid inside eachexterior canister pipe 41, it eventually reaches the canister pipechamber 44 that contains a horizontal weir 9. As the liquid levelcontinues to increase, liquid fills the canister pipe chamber 44 andbegins to spill over the horizontal weir 9 into the interior canisterpipe 45 associated with that exterior canister pipe 41. As the liquidcontinues to spill over the horizontal weir 9 and down the interiorcanister pipe 45, it has sufficient velocity to create negative pressurein the canister pipe chamber 44. The negative pressure allows trappedair within the canister pipe chamber 44 to be conveyed, with the liquid,through the interior canister pipe 45 and into the canister cavity 26.This process continues until all the air in the canister pipe chamber 44is removed thus creating liquid communication between the exteriorcanister pipe 41 and interior canister pipe 45. The resulting liquidcommunication shall herein be referred to as the exterior siphon and theprocess of removing the air from the canister pipe chamber 44, theinterior canister pipe 45 and the exterior canister pipe 41 is referredto as “priming” the exterior siphon. Siphoned liquid exits the interiorcanister pipe 45 via the interior bottom orifice 64 and begins to fillthe canister cavity 26.

For priming of the exterior siphon to occur and to achieve stable siphonflow the canister pipe chamber 44 must be constructed in accordancewithin the parameters of a design ratio. As shown in FIG. 11 and FIG.12, the canister pipe chamber 44 has a width b and a height h.Optimally, the canister pipe chamber 44 has a width to height ratio b/hin the range of 1 to 4. However, a width to height ratio b/h in therange of 0.25-8.0 will be functional.

A nappe deflector 49 may be affixed to the wall of the interior canisterpipe 45 facing radially inward towards the center of the exemplaryfiltration device 70 such that it will increase the horizontaltrajectory of the liquid. The additional horizontal trajectory reducesthe siphon priming time by decreasing the available area for air tore-enter the canister pipe chamber 44 as the siphon is established.

The canister cavity 26 encompasses the sealed space between the canister22 and the baseplate 2. Within the canister cavity 26 the filter media42 is contained between the media basket 40 and the inner partitionscreen 38. The media basket 40 and inner partition screen 38 arecircumferential vertical screens that allow the passing of liquid butnot the filter media 42. Contaminated liquid passes through the filtermedia 42 horizontally until it reaches the permeable support column 24which contains the center riser pipe 8. Siphoned liquid will continue tofill the canister cavity 26 until it reaches the canister ceiling 68.The air from the canister cavity 26 is displaced by the liquid and exitsvia the center riser pipe 8 and outlet pipe 7. Once liquid fills thecanister cavity 26, the liquid enters into the interior void space ofthe cap 6. The inlet of the center riser pipe 8 is located mediallywithin the small void space on the interior of the cap 6 and above thecanister ceiling 68. Fluid enters the center riser pipe 8 via the inlet,which is a horizontal orifice on the top of the center riser pipe 8 thatacts as a weir to transmit liquid from inside the cap 6. The inlet weirmay be flared or serrated to increase the weir length and thus increasethe spill flow rate. As liquid begins to spill over the weir of thecenter riser pipe 8, it is transmitted vertically downward. When thedownward flow has sufficient velocity it creates negative pressureinside the void space of the cap 6 thus transmitting air down the centerriser pipe 8 and into the outlet pipe 7. When all of the air is removedfrom the void space of the cap 6 a siphon is formed and liquidcommunication is established between the canister cavity 26, cap 6, andthe center riser pipe 8. This liquid communication shall herein bereferred to as the inner siphon. When liquid reaches the bottom of thecenter riser pipe 8 it is conveyed into an affixed outlet pipe 7. Fluidis conveyed through the outlet pipe 7 and into an optional outletmanifold 30. The outlet manifold 30 is a series of outlet pipes thatconnect in parallel to allow multiple exemplary filtration devices 70 tobe connected in parallel. Fluid exits the outlet pipe 7 (and optionaloutlet manifold 30) and is conveyed out of the containment structure viaa downstream pipe 31.

For priming of the interior siphon to occur and to achieve stable siphonflow, the central riser pipe 8 and the area under the cap 6 must beconstructed in accordance within the parameters of a design ratio. Asshown in FIG. 11 and FIG. 12, the outlet of the center riser pipe 8 hasan outlet area A. A passage area A_(y) is defined as a verticalcross-sectional area above the center riser pipe outlet and below thecap. An entrance ring area A_(r) is defined as a horizontalcross-sectional area between the cap 6 and the top of the center riserpipe 8. To ensure priming of the interior siphon, a ratio A_(y)/A has avalue in a range from 1.0 to 22.5 and a ratio A_(r)/A has a value in arange from 1.0 to 22.0.

The exemplary filtration device 70 utilizes two distinct siphons thatestablish liquid communication between the containment structure 1,canister cavity 26, center riser pipe 8, and the outlet pipe 7. Asliquid ceases to enter the containment structure 1, the siphons in theapparatus continue to operate thus drawing down the liquid level in thecontainment structure 1. Once the liquid in the containment structure 1reaches the exterior bottom orifice 62 of the exterior canister pipe 41,it allows the introduction of air into the canister pipe chamber 44. Theair accumulates in the canister pipe chamber 44 and will eventuallybreak the liquid connection between the exterior canister pipe 41 andthe interior canister pipe 45, thus ceasing the outer siphon. Once theouter siphon is broken the inner siphon will cease as it no longer hasliquid communication with the containment structure 1. At this instancethe liquid in the canister 22 has a higher elevation than the liquid inthe containment structure 1 and an unbalanced hydraulic force exists.Fluid will than reverse direction and flow from the canister cavity 26through the exterior canister pipes 41 and interior canister pipes 45and back into the containment structure 1. Fluid inside the canistercavity 26 is replaced by air from the now empty outlet pipe 7. A reverseouter siphon will develop and liquid will flow out of the canistercavity 26 until it reaches the interior bottom orifice 64 of theinterior canister pipe 45. This back-flushes the exemplary filtrationdevice 70, removing contaminant particles from the filter media 42 outinto the containment structure 1. This extends the life of the filtermedia 42. Air from the canister cavity 26 will be introduced into theinterior canister pipe 45 and fill the canister pipe chamber 44 causingthe reverse outer siphon to cease. Any remaining water inside theexemplary filtration device 70 will slowly drain down via the leachorifice 48. The operation cycle of the exemplary filtration device 70 isnow complete and the canister cavity 26 will be empty of liquid andready for the next operation cycle.

What is claimed is:
 1. A filtration device comprising: a baseplate; asupport column coupled to the baseplate, the support column permeable toliquids; a canister with one or more sides and a ceiling defining acavity, the canister detachably coupled to the baseplate; a center riserpipe coupled to the baseplate and positioned within the support column,with an inlet at a top of the center riser pipe, wherein the centerriser pipe inlet is above the canister ceiling; a canister pipe fixed inone of the sides of the canister, the canister pipe comprising anexterior canister pipe and an interior canister pipe separated by aweir, wherein the exterior canister pipe and the interior canister pipeopen into a chamber in a top portion of the canister pipe above theweir; an exterior bottom orifice in a bottom portion of the exteriorcanister pipe communicating with an environment external to thefiltration device; and an interior bottom orifice in a bottom portion ofthe interior canister pipe communicating with the canister cavity. 2.The filtration device of claim 1, further comprising: a cap positionedon top of the canister ceiling with a void space under the cap, whereinthe top of the center riser pipe is positioned within the void spaceunder the cap.
 3. The filtration device of claim 2, further comprising acenter riser pipe outlet with an outlet area A; wherein a passage areaA_(y) is defined as a vertical cross-sectional area above the centerriser pipe outlet and below the cap; wherein an entrance ring area A_(r)is defined as a horizontal cross-sectional area between the cap and thetop of the center riser pipe; wherein a ratio A_(y)/A has a value in arange from 1.0 to 22.5; and wherein a ratio A_(y)/A has a value in arange from 1.0 to 22.0.
 4. The filtration device of claim 2, wherein thecanister pipe chamber has a height h and a width b; and wherein a ratiob/h has a value in a range from 0.25 to
 8. 5. The filtration device ofclaim 2, further comprising: a canister gap between the canister and amedia basket.
 6. The filtration device of claim 2, further comprising: acolumn gap between the center riser pipe and the support column.
 7. Thefiltration device of claim 2, further comprising: a column supportflange in a top portion of the support column and a cap gasket on a topsurface of the column support flange; a baseplate gasket between thebaseplate and the canister; wherein the support column penetrates acanister top opening in the canister ceiling; and wherein the cap isconfigured to detachably couple to the support column and to compressthe canister against the cap gasket and the baseplate gasket.
 8. Thefiltration device of claim 1, further comprising: a leach orifice in abottom portion of the center riser pipe.
 9. The filtration device ofclaim 1, wherein the canister ceiling contacts a top of a media basket.10. The filtration device of claim 1, further comprising: a nappedeflector on the top portion of the weir and inside the interiorcanister pipe.
 11. The filtration device of claim 1, wherein thefiltration device is configured to establish a first siphon to conveyliquid from the exterior bottom orifice through the interior bottomorifice into the canister cavity when a liquid level outside thefiltration device is higher than the top of the weir; and wherein thefiltration device is configured to establish a second siphon to conveyliquid from canister cavity through the top of the center riser pipe andout an outlet pipe when the first siphon has been established and theliquid level outside the filtration device is higher than the top of thecenter riser pipe.
 12. The filtration device of claim 11, wherein thefiltration device is configured to break the first siphon when theliquid level outside the filtration device is lower than the exteriorbottom orifice, then break the second siphon when a liquid level insidethe support column is lower than the top of the center riser pipe. 13.The filtration device of claim 12, wherein the filtration device isconfigured such that once the second siphon breaks, then the filtrationdevice will establish a reverse siphon, drawing the liquid inside thecanister cavity in through the interior bottom orifice, through theinterior canister pipe through the exterior canister pipe and outthrough the exterior bottom orifice, back-flushing particulate matterfrom the canister cavity.